Press

ABSTRACT

Press with counterbalanced ram mounted for longitudinal reciprocation in a frame, a pitman being coupled to the ram and connected to a crankshaft for pivotal movement with respect to a first axis spaced from the axis of rotation of the crankshaft, a counterweight for the ram being mounted for longitudinal reciprocation and being aligned with the ram, and a pitman assembly coupled to the counterweight and connected to the crankshaft for pivotal movement with respect to a second axis spaced from the axis of rotation of the crankshaft and in a direction opposite the direction of spacing of the first axis.

United States Patent Inventors Daniel W. Marsh; [56] References Cited Bertram W. Perkins, 17-, both of Warren, UNITED STATES PATENTS App No 221 3 2,321,325 6/1943 Sherman et al. 100/282 ux Filed Sept. 29, 1969 3,450,038 6/1969 Kraft et al 100/282 X Patented Oct. 12, 1971 Primary Examiner-Billy J. Wilhite Assignee Perkins Machine Company Attorney-W. R. l-lulbert Warren, Mass.

ABSTRACT: Press with counterbalanced ram mounted for .12-.. ,1 a longitudinal reciprocation in a frame, a pitman being coupled to the ram and connected to a crankshaft for pivotal move- 6 D ment with respect to a first axis spaced from the axis of rotaalms rawmg tion of the crankshaft, a counterweight for the ram being [1.8. CI 100/214, mounted for longitudinal reciprocation and being aligned with 72/450, 72/456, 83/615, 100/282 the ram, and a pitman assembly coupled to the counterweight lnt.Cl B30b l/06 and connected to the crankshaft for pivotal movement with Field of Search [00/214, respect to a second axis spaced from the axis of rotation of the 282; 72/450, 456; 83/615; 18/16 M; 74/44, 52, crankshaft and in a direction opposite the direction of spacing of the first axis.

7e 90 77 l l 943 881 sum 3 or a .PATENTED BUT I 2 I97! 1 PRESS This invention relates to presses in which a ram is caused to reciprocate upon rotation of a crankshaft.

A primary object of the invention is to reduce the vibration of the press normally attendant reciprocation of the ram, making possible more strokes per unit of time. Other objects are to eliminate both longitudinal and transverse vibration, in a simple, inexpensive, and reliable manner, even when the weight of a tool carried by the ram changes.

The invention features a ram mounted for longitudinal reciprocation in a frame, a pitman coupled to the ram and connected to a crankshaft for pivotal movement with respect to a first axis spaced from the axis of rotation of the crankshaft, a counterweight for the ram mounted for longitudinal reciprocation and aligned with the ram, and a pitman assembly coupled to the counterweight and connected to the crankshaft for pivotal movement with respect to a second axis spaced fromthe axis of rotation of the crankshaft in a direction opposite the direction of spacing of the first axis from the axis of rotation. In preferred embodiments the counterweight is coupled to the crankshaft through a pair of pitmans straddling the ram pitman, the counterweight pitmans being of higher density material (preferably bronze) than the ram pitman and being of extended width, thereby serving to counterbalance (both longitudinally and transversely) the ram pitman and its coupling to the ram; the first and second axes are equally spaced from the axis of rotation of the crankshaft; the counterweight generally equals in weight the ram (including 'all associated parts that engage in strictly longitudinal reciprocation); the counterweight pitmans equal in weight the ram pitman (including all associated parts that engage in and combined longitudinal and transverse reciprocation); and the counterweight is mounted for reciprocation along gibs and is adapted to receive a selected supplementary weight to balance a selected tool mounted on the ram.

Other objects, features, and advantages of the invention will appear from the following description of a preferred embodiment thereof, taken together with the attached drawings thereof, in which:

FIG. 1 is an elevational view partially broken away, of portions of a press;

FIG. 2 is a sectional view along 2--2 of FIG. 1;

FIG. 3 is a sectional view along 3-3 of FIG. 1;

FIG. 4 is an elevational view of the crankshaft, partially broken away;

FIG. 5 is a plan view of a counterweight pitman, and

FIG. 6 is a plan view of the ram pitman.

Ram 10 is mounted between gibs 12, 14 which extend into bronze-lined V-grooves 16, 18 (see especially FIG. 3) in the ram, for longitudinal reciprocation toward and away from bed 20 fixed in frame 22. The gibs are supported on frame 22.

Crankshaft is mounted in frame 22 for rotation about axis 32 (FIG. 4), is driven by a motor (not shown) through clutch and flywheel assembly 34 and is controlled by brake 35. Pitman 38, with cap 39 (FIG. 6) is pivotally connected to crankshaft pin 40 having an axis 42 (FIG. 4) offse't from and parallel to axis 32. Adjustment screw 50 (FIG. 1), having a ball end 52, is threaded in the end of pitman 38 opposite shaft 30 and is secured by clamp 54. Ball 52 is secured between ball seat 56 and cap 57, the seat and cap being mounted in the ram so that all motion of the ball is pivotal about a center having a fixed position relative to the ram.

Identical bronze pitmans 60 and 62, having caps 61 and 63 (one pitman and cap being shown in detail in FIG. 5), are respectively pivotally connected to pins 64 and 66 of crankshaft 30, these pins being symmetrically spaced on opposite sides of pin 40 and having a common axis 68 coplanar with axes 32 and 42 and offset from axis 32 in the opposite direction from and by a distance equal to the offset of axis 42. The other ends of pitmans 60 and 62 are pivotally secured in recesses 74 and 75 of counterweight 76 by pin8l in turn held in place by retaining rings 82, 83. A recess 88 is provided at the top of counterweight 76 to receive a selected replaceable weight 90 held in place by screw 92 received in hole 94. Counterweight 76 is mounted between gibs 77 and 78 carried on frame 22 and extending into V-grooves 79, (see especially FIG. 2) in the sides of the counterweight.

The combined weight of pitmans 60 and 62 equals that of pitman 38 and screw 50 (this balance being facilitated by the high density of the two bronze pitmans and by the extended width of those pitmans, encompassing side portions 98 and 99 which are not required structurally and are present only to increase the weight of the pitmans). The weight of counterweight 76 equals that of ram 10 (including all hardware that, with the ram, engages in exclusively longitudinal reciprocation, except for any tool that may be attached to the ram for cooperation with a mating tool mounted in plate 20, neither such tool being shown in the drawings). The weight of replaceable weight is chosen to equal that of any tool attached to the ram (e.g., a die). y

In operation, as crankshaft 30 rotates about axis 32, the rotation of axes 42 and 68 about axis 32 causes pitmans 38, 60, and 62 to undergo motion having'components of longitudinal and transverse reciprocation, and to produce strictly longitudinal reciprocation of ram 10 and counterweight 76. By virtue of the spacing of the axes, the longitudinal motion of pitman 38 is equal in distance but always opposite in direction to that of pitmans 60 and 62. As a result, counterweight 76 and ram 10 reciprocate in opposite longitudinal directions so that no net longitudinal force is applied to the frame. Similarly, the longitudinal and transverse motions of pitman 38 (including screw 50) balances those of pitmans 60 and 62, so that no net force in any direction is applied to the frame. Finally, the movement of weight 90 balances that of the tool on ram 10, so that no substantial machine vibration occurs.

Other embodiments (e. g, in which the weights of the ram and counterweight are unequal, and a compensating difference is introduced in the spacings of axes 42 and 68 from axis 32 to preserve the desired balance) will occur to those skilled in the art and are within the following claims.

What is claimed is:

1. A press having a bed,

a ram mounted for longitudinal reciprocation toward and away from said bed,

a crankshaft mounted to be driven in rotation about a first axis,

a first pitman assembly coupled to said ram and connected to said crankshaft for pivotal movement with respect to a second axis spaced from said first axis,

a counterweight for said ram mounted for longitudinal reciprocation and aligned with said ram, and

a second pitman assembly coupled to said counterweight and connected to said crankshaft for pivotal movement with respect to a third axis spaced from said first axis in a direction opposite the direction of said spacing of said second axis,

said counterweight being adapted to receive a selected supplementary weight to balance a selected tool mounted on said ram.

2. The press of claim 1 wherein each said pivotal movement of a said pitman assembly includes longitudinal and transverse components of reciprocation, the longitudinal components of said respective assemblies occuring in opposite directions, the transverse components of said respective assemblies occuring in opposite directions, said assemblies being of relative weights chosen so that forces associated with said respective longitudinal and transverse components balance each other.

3. The press of claim 1 wherein said first pitman assembly comprises a ram pitman, said second pitman assembly comprises two counterweight pitmans which straddle said ram pitman, said counterweight pitmans being of higher density material than said ram pitman.

4. The press of claim 3 wherein each of said two counterweight pitmans includes side portions not structurally required and present only to increase the weight of said two counterweight pitmans.

first axis is midway between said second and third axes, and said counterweight and said ram are of equal weight.

7. The press of claim 1 wherein said counterweight is recessed to receive said supplementary weight.

8. The press of claim 1 wherein said counterweight is mounted for reciprocation along gibs. 

1. A press having a bed, a ram mounted for longitudinal reciprocation toward and away from said bed, a crankshaft mounted to be driven in rotation about a first axis, a first pitman assembly coupled to said ram and connected to said crankshaft for pivotal movement with respect to a second axis spaced from said first axis, a counterweight for said ram mounted for longitudinal reciprocation and aligned with said ram, and a second pitman assembly coupled to said counterweight and connected to said crankshaft for pivotal movement with respeCt to a third axis spaced from said first axis in a direction opposite the direction of said spacing of said second axis, said counterweight being adapted to receive a selected supplementary weight to balance a selected tool mounted on said ram.
 2. The press of claim 1 wherein each said pivotal movement of a said pitman assembly includes longitudinal and transverse components of reciprocation, the longitudinal components of said respective assemblies occuring in opposite directions, the transverse components of said respective assemblies occuring in opposite directions, said assemblies being of relative weights chosen so that forces associated with said respective longitudinal and transverse components balance each other.
 3. The press of claim 1 wherein said first pitman assembly comprises a ram pitman, said second pitman assembly comprises two counterweight pitmans which straddle said ram pitman, said counterweight pitmans being of higher density material than said ram pitman.
 4. The press of claim 3 wherein each of said two counterweight pitmans includes side portions not structurally required and present only to increase the weight of said two counterweight pitmans.
 5. The press of claim 3 wherein said two counterweight pitmans and said first pitman assembly are of generally equal weight, said first axis is midway between said second an third axes, and all portions of said first pitman assembly undergo combined longitudinal and transverse reciprocation during operation of said press.
 6. The press of claim 1 wherein said axes are coplanar, said first axis is midway between said second and third axes, and said counterweight and said ram are of equal weight.
 7. The press of claim 1 wherein said counterweight is recessed to receive said supplementary weight.
 8. The press of claim 1 wherein said counterweight is mounted for reciprocation along gibs. 